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Do the rheological properties of compliant weak rocks dominate the seismic response of the upper volcanic edifice?

Christopher J. Bean 1, Ivan Lokmer2

  • Affiliations: 1Geophysics Section, Dublin Institute for Advanced Studies (DIAS), Ireland  2School of Earth Sciences, University College Dublin, Ireland

  • Presentation type: Poster

  • Presentation time: Thursday 16:30 - 18:30, Room Poster Hall

  • Poster Board Number: 130

  • Programme No: 2.1.40

  • Theme 2 > Session 1

Abstract

The upper volcanic edifice plays a crucial role in influencing the final stage of the magma migration pathway to the Earth's surface. It is commonly expected that this migration will produce a distinct seismic response, which can be tracked through the shallow subsurface. As a result, shallow Long Period (LP) seismicity and volcanic tremor capture lots of interest of the scientific community, related to hazard assessments. However, a detailed analysis of LP and tremor signals reveals that these types of events can be generated in ways that do not necessarily involve migrating fluids. Additionally, it has long been recognized that a brief period of quiescence often precedes eruptions, which remains puzzling if seismicity-related fluids are nearing the surface. In this study, we examine the role of compliant and weak rocks, which are typical in upper volcanic settings, on the seismic response and seismicity generation. We demonstrate that many of the observed characteristics of pre-eruptive seismicity can be explained by considering the rheology of the upper edifice. This analysis also highlights the presence of exceptionally weak structures at the scale of the entire edifice.